Method of operating a scraper having a manipulatable apron

ABSTRACT

In a scraper having an apron which may be advanced and retracted relative to the bowl in addition to being raised and lowered to provide a hoeing action and having a bucket type of ejector which may be advanced and retracted in the bowl, highly efficient loading is realized by advancing the ejector to receive the material which is loaded by the apron in the initial portion of the cycle and then retracting the ejector to move such material to the rear of the bowl thereby facilitating subsequent loading at the front of the bowl. During ejection, the apron may be scraped down along the forward surface of the ejector to dislodge material.

United States Patent Peterson 1 1 3,707,048 [451 -Dec. 26,1 972 [54] METHOD OF OPERATING A SCRAPER HAVING A MANIPULATABLE APRON [72] Inventor: Robert A. Peterson, San Leandro,

Calif.

[60] Division of Ser. No. 589,978, Oct. 27, 1966, Pat. No. 3,471,952, and a continuation of Ser. No. 839,414, July 7, 1969, abandoned.

. 9/1943 Daniels ..37/126 3,006,088 10/1961 Layton ..37/129 3,077,681 2/1963 Peterson ..37/129 2,278,329 3/1942 Mccollumm ..37/l26 3,073,044 1]] 963 Bernotas ..37/1 29 3,105,311 10/1963 Hait ..37/4

Primary Examiner-Robert E. Pulfrey Assistant Examiner-C. W. Hanor Attorney-Fryer, Tjensvold, Feix, Phillips & Lempio [5 7] ABSTRACT In a scraper having an apron which may be advanced and retracted relative to the bowl in addition to being raised and lowered to provide a hoeing action and having a bucket type of ejector which may be advanced and retracted in the bowl, highly efficient loading is realized by advancing the ejector to receive the material which is loaded by the apron in the initial portion of the cycle and then retracting the ejector to move such material to the rear of the bowl thereby facilitating subsequent loading at the front of the bowl. During ejection, the apron may be scraped down along the forward surface of the ejector to dislodge material.

1 Claim, Drawing Figures PATENTED DEC 26 1912 SHEET 1 [IF 3 I NVEN TOR.

PATENTED DEC 2 5 I972 SHEET 2 [IF 3 PATENTEDneczs I972 sum 3 or 3 INVENTOR. ROBERT A. PETERSON METHOD OF OPERATING A SCRAPER HAVING A MAN IPULATABLE APRON CROSS REFERENCE TO RELATED APPLICATION This application is a division of copending application Ser. No. 589,978 of Robert A. Peterson filed Oct.

27, 1966 now US. Pat. No. 3,471,952 and entitled BACKGROUND OF THE INVENTION This invention relates to earthworking equipment and more particularly to tractor drawn scrapers of the class having a load carrying bowl with a cutting edge for directing earth into the bowl. The invention provides a multiply jointed apron assembly which may be manipulated through a variety of movements to provide for self loading, to facilitate ejection, and for other purposes.

A conventional earthmoving scraper depends upon the forward motion of the vehicle to force earth from the cutting blade up into the load carrying bowl. As the contents of a partially filled bowl offers substantial resistance to the entrance of additional material it has usually been necessary to make use of a pusher tractor, in addition to the tractor which draws the scraper, in order to completely fill the bowl so that the full load carrying capacity of the scraper is utilized. As this practice is costly and inefficient a variety of self loading scrapers have been developed.

The most commonly used form of self loading scraper is provided with a chain and flight elevator structure at the forward face of the bowl and above the cutting edge. The elevator functions to continually carry earth away from the immediate region of the cutting edge and thus lessens the resistance to entrance of additional soil into the bowl. Under many conditions, the elevator enables complete filling of the bowl without employing supplementary motive power.

However elevator equipped self loading scrapers have been found to be subject to certain operating problems of their own. The elevator limits the size of the entrance opening into the bowl and thereby prevents the loading of boulders or other objects which are larger than some specific size. Further the elevator is particularly susceptible to jamming and damage from large boulders or other similar obstructions. Certain types of soils and soil conditions seriously interfere with elevator operation. Still another problem is encountered in that there are conditions under which the elevator will not insure full loading of the bowl and it becomes desirable to utilize a pusher tractor as with a conventional scraper. As the elevator partially obstructs the front of the scraper bowl, push loading is inefficient. Although multiple elevator speeds can be provided, the rate at which material is forced into the bowl by push loading is difficult to coordinate with that of the elevator.

To avoid some of these problems a second general class of self loading scraper has heretofore been proposed. Instead of an elevator, such scrapers have an apron mounted at the open front of the bowl in such a manner that it may be pivoted upward and downward and may be reciprocated in a horizontal direction. The

apron may thus be made to undergo a kind of raking or hoeing motion to pull material into the bowl from the region of the blade. Scrapers of this class are not extensively used in the industry at present. This results at least in part from operational limitations of the apron' manipulating mechanism as heretofore designed. The mechanism has been cumbersome while providing for only a very restricted variety of motions thereby limiting its utility for facilitating loading and preventing its use for other scraper operations.

SUMMARY OF THE INVENTION The present invention is a scraper having a manipulatable apron mounted at the bowl by a multiply articulated structure with independent powered control of flexing at each joint so that the apron may be made to undergo a variety of movements within the bowl, above the bowl, and forwardly therefrom. The extreme degree of manipulatability and the range of apron positions obtainable with this structure greatly facilitates a variety of scraper functions.

The apron of this invention may be readily manipulated to scoop material across the blade and into the bowl with any kind of a linear or curvilinear motion which may be appropriate to the circumstances and at any desired elevation with reference to the blade. The structure facilitates a kindv of progressive loading in which the ejector is initially moved to a forward position in the bowl and loaded by the above described scooping action of the apron, after which the ejector is moved rearwardly carrying the contained material to the rear of the bowl and leaving the forwardportion thereof available for receiving additional material. The apron may readily be lifted as high as might be necessary to receive boulders and other large objects into the bowl and may further be employed to reach forward and over such objects to forcibly load the object into the bowl. I

The manipulatable apron may be lifted completely above the bowl during ejection of the load and may be moved down along the face of the ejector in a scraping movement to remove any lodged or sticky material therefrom.

Accordingly it is an object of this invention to provide a more versatile earthmoving scraper.

It is another object of this invention to provide a self loading scraper free from fixed mechanism restricting the opening at the load carrying bowl.

It is still another object of this invention to provide a more efficient and flexible self loading mechanism for earthmoving scrapers.

It is a further object of the invention to provide a self loading scraper which may be push loaded without complications or problems where soil conditions make such operation necessary.

It is still another object of the invention to provide a self loading mechanism for a scraper which may be completely lifted from the bowl of the scraper during ejection of the contents thereof and which may be utilized to facilitate such ejection.

Still a further object of this invention is to provide a self loading earthmoving scraper having powered mechanism for facilitating the loading of large boulders and similar objects.

An additional object of the invention is to provide a self loading mechanism for an earthmoving scraper which may be used in conjunction with the ejector thereof to facilitate complete filling of the bowl of the FIG. 3 is an additional side elevational view of the scraper structure of FIG. 1 showing certain mechanisms thereof in moved positions for the purpose of facilitating loading of the scraper.

Referring now to the drawing and more particularly to FIGS. 1 and 2 in conjunction, a scraper of the class to which the invention is applicable has a load carrying bowl 11 generally formed by'a floor 12, sidewalls 13, and with the rearwall being formed by a movable ejector 14, the top and the forward face of the bowl being open. The cutting edge is formed by a blade 16 extending forwardly and downwardly from the front edge of floor 12. The bowl 11 is supported at the back end by frame members 17 which extend to the rear wheel assembly 18 of the scraper. The bowl ll'is supported at the forward end by a pair of draft arms 19 which extend a from a tractor hitch 21 back along each side of the 'bowl and which are connected thereto by pivots 22 situated at a central position on the bowl sidewalls 13. The tractor which draws the scraper through hitch 21 and the rearwheel assembly 18 of the scraper may be of conventional construction and accordingly will not be herein described. 3

The bowl sidewalls 13 extend a substantial distance forward from the position of the cutting edge 16 and a cross beam 23 extends between the two sidewalls at the forward end thereof and at a level well above'that of the cuttingedge. Raising and lowering of the bowl 11 is effected by a pair of hydraulic jacks 24 connected between the cross beam 23 and a pair of arms 26 projecting rearwardly and upward from the tractor hitch 21. Extension of jacks 24 thus pivots the entire bowl assembly ll downward about the axis of rear wheels 18 to cause the cutting edge 16 to bite into the ground surface 27. Forward rnotion of the scraper then causes a superficial layer of earth to be carried up over the edge 16 and into the bowl 11. When the bowl 11 has been filled jacks 24 are contracted pivoting the bowl upward about rear wheels 18 into the load carrying position at which the scraper may travel at a relatively high speed 7 to transport the earth away from the site. Discharge of the contents of the bowl 11 is accomplished by extension of a second pair of jacks 28, connected between the ejector l4 and'the rear wheel assembly 18, which move the ejector forward towards the cutting edge 16.

In order to utilize completely the load carrying capacity of the bowl 11, means must be provided to hold the material therein at the open forward end. In a conventional scraper a singly pivoted apron closure is used for this purpose and most self loading scrapers employ an earth elevator extending upwardly at the front of the bowl.

be desirable to facilitate scooping of material into thebowl l1 and to assist other scraper operations.

Considering now the detailed structure of apron support assembly 31, a pair of arms 32 are situated one on each side of the bowl 11 with the lower end of each arm being coupled thereto by pivots 33. A cylindrical cross member 34 connects the opposite end of arms 32 above the bowl sidewalls 13 which preferably have a circular profile at the upper edge to maximize load carrying capacity while providing for pivoting of the arms 32 and cross member 34 about pins 33.

An extension 36 projects a short distance from the upper end of each arm 32, at an angle with. respect thereto, to pivotally connect with one end of an intermediate frame section 37. at pivots 38. Frame section 37 is formed by side members 39 which are connected by a series of transverse tubular reinforcing members 42. In addition to reinforcing the intermediate frame section 37, the tubular cross members 42 serve to aid in retaining material at the forward end of the bowl 11 when the apron 29 is moved to the load carrying position. Apron 29, which has an arcuate profile, is coupled to the end of intermediate framesection 37 opposite pivots 38 by an additional set of pivots 43 near the upper edge of the apron.

'Thus complete flexibility of movement of the apron 29 in the forward, rearward, vertical, and angular directions is afforded inasmuch as the apron may be pivoted with respect to intermediate frame 37, which-in turn may pivot with respect to the arms 32, and the arms 32 are in turn pivotable about a transverse axis through thebowl. Mechanism for effecting and controlling such motion includes a first pair of double acting hydraulic jacks 44 each being coupled to one of the arms 32 at a pivot 46 situated at an'interme diate point therealong and being coupled at the opposite end to a side wall 13 of the bowl 1.1 at a pivot 47 situated rearwardly from the pivot 46. Extension of jacks 44 therefore pivots the arms 32 forwardly while retraction of the jacks 44 swings the arms to the rear.

Pivoting of the intermediate frame section 37 relative to arms 32 is controlled by a second pair of jacks 48 each of-which is connected between a pivot 49 at an intermediate point on one of the arms 32 and a pivot 51 on one of a pair of triangular pivot bracket assemblies 52 secured to the intermediate frame section 37 at the end thereof closest to arms 32. A pair of stops 55 formed by a portion of the bracket assemblies 52 are positioned to contact the top edges of the bowl side walls 13 to limit inward pivoting of the apron assembly.

A corner of each pivot bracket assembly 52 projects upwardly and an end of one of a third pair of double acting hydraulic jacks 53 is pivotally coupled thereto. The opposite end of each jack 53 is pivoted to an arm 54 which extends a short distance upward from the apron 29. Thus the third set of jacks 53 may be utilized to pivot the apron 29 with respect to the intermediate frame section 37. The three sets of hydraulic jacks 44, 48 and 53 are preferably controlled from the operators station of the tractor which draws the scraper, suitable control systems for such jacks being understood within the art.

Considering now typical manipulations of the apron 29 which may advantageously be made during operation of the scraper, extension of jacks 44 accompanied by a partial extension of jacks 48 and 53 will position the apron 29 at the cutting blade 16 with the upper edge of the apron being situated above and forwardly therefrom as illustrated in FIG. 1 in particular. This is the normal position of the apron for transporting a load. Referring now to FIG. 3 further extension of jacks 48, generally accompanied by contraction of jacks 53, positions the lower edge of the apron 29 forwardly from the cutting edge 16 and slightly above the cutting edge so that the edge may bite into the surface soil layer 27 and guide soil backwardly into the bowl 11. At this stage of operation soil will tend to mound up immediately above the cutting edge 16 and movement of such soil back into the bowl 11 may be assisted by contracting jacks 44 and 48 while extending jacks 53 so that the apron 29 performs a kind of scooping motion back into the position illustrated at 29'. This movement of the apron 29 may be cyclically repeated during loading of the scraper bowl 11 while the scraper is in motion, and will generally eliminate any need for use of a pusher tractor with the scraper.

Referring now again to FIG. 1, the availability of the kind of apron motion described above facilitates an advantageous use of the ejector 14 to assist loading. In particular, at the start-of loading the jacks 28 may be actuated to move ejector l4 forward so that the lower edge of the ejector is adjacent the cutting blade 16. Apron 29 may then be manipulated to load soil onto the ejector 14 after which jacks 28 are contracted to draw the ejector to the rear of the bowl carrying the soil with it. Thus in contrast to a conventional scraper the initial loading is at the rear of the bowl leaving the forward portion unobstructed and capable of receiving additional soil without resistance. Ejector 14 preferably has sidewalls 56 to facilitate such use of the ejector in carrying material to the rear of the bowl 1 1.

During discharge of the soil from bowl ll apron 29 may be lifted completely above the bowl by contracting jacks 44 while extending jacks 48 as illustrated at 29" in FIG. 1. Ejector 14 may then be driven forward by extension of jacks 28 to force the contents of the bowl out of the open forward end thereof. Should soil or other materials stick to the ejector l4, jacks 48 and 53 may be progressively contracted while jacks 44 are gradually extended to cause the lower end of apron 29 to sweep downward and forward along the face of the ejector and forcibly wipe lodged material therefrom.

It will be apparent that by the appropriate operation of the several jacks 44, 48 and 53 various other operations may be accomplished. For example the apron 29 may extend forwardly from the cutting edge 16 above some large object such as a boulder and may then be utilized to draw the object back and up into the bowl 1 1.

While the invention has been disclosed with respect to a specific embodiment for purposes of example it will be apparent that numerous modifications are possible within the scope of the invention and it is not intended to limit the invention except as defined in the following claims.

at is claimed is:

1. In a method for discharging material from a scraper which has a bowl with a cutting edge and which has an ejector that is advanced towards said cutting edge to force material from said bowl, said ejector being of the form having an upwardly extending portion defining the rear wall thereof and having a lower forwardly extending portion rigidly joined to said upwardly extending portion and capable of receiving and supporting material, and which has an apron with a lower end which is manipulatable within said bowl and may be simultaneously moved downward and forward therein while said ejector is at said advanced position thereof, the steps comprising:

lifting said apron from said edge to a position whereby said lower end is above said bowl, and moving said apron rearwardly to a position above the advanced ejector position,

advancing said ejector toward said edge to discharge the material not supported by said ejector from said bowl, and

sweeping said lower end of said apron downward and forward along the surfaces of said ejector. 

1. In a method for discharging material from a scraper which has a bowl with a cutting edge and which has an ejector that is advanced towards said cutting edge to force material from said bowl, said ejector being of the form having an upwardly extending portion defining the rear wall thereof and having a lower forwardly extending portion rigidly joined to said upwardly extending portion and capable of receiving and supporting material, and which has an apron with a lower end which is manipulatable within said bowl and may be simultaneously moved downward and forward therein while said ejector is at said advanced position thereof, the steps comprising: lifting said apron from said edge to a position whereby said lower end is above said bowl, and moving said apron rearwardly to a position above the advanced ejector position, advancing said ejector toward said edge to discharge the material not supported by said ejector from said bowl, and sweeping said lower end of said apron downward and forward along the surfaces of said ejector. 